Chapter 1 
1 Introduction 
Work Unit Objective and Monitoring Approach 
The objective of the Periodic Inspections work unit in the Monitoring Com- 
pleted Navigation Projects (MCNP) research program is to periodically monitor 
selected coastal navigation structures to gain an understanding of the long-term 
structural response of unique structures to their environment. These periodic 
data sets are used to improve knowledge in design, construction, and mainte- 
nance of both existing and proposed future coastal navigation projects. These 
data also will help avoid repeating past design mistakes that have resulted in 
structure failure and/or high maintenance costs. Past projects monitored under 
the MCNP Program, and/or structures with unique design features that may have 
application at other sites, are considered for inclusion in the Periodic Inspections 
monitoring program. Selected sites are presented as candidates for development 
of a periodic monitoring plan. Those sites receiving favorable response during 
MCNP program review are inspected and a monitoring plan is developed and 
presented for approval. Once the monitoring plan for a site is approved by the 
field review group and funds are provided, monitoring of the site is initiated. 
Normally, base conditions are established and documented in the initial effort. 
The site then is reinspected on a periodic basis (frequency of surveys is based on 
a balance of need and funding for each monitoring site) to obtain long-term 
structural performance data. 
Relatively low-cost remote sensing tools and techniques, with limited ground 
truthing surveys, are the primary inspection tools used in the monitoring efforts. 
Most periodic inspections consist of capturing above-water conditions of the 
structure at periodic intervals using high-resolution aerial photography. Periodic 
aerial photographs are compared visually to gauge the degree of in-depth analy- 
sis required to quantify structural changes (primarily armor unit movement). 
Data analysis involves using photogrammetric techniques developed for and 
successfully applied at other coastal sites. At sites where local wave data are 
being gathered by other projects and/or agencies, and these data can be acquired 
at a relatively low cost, wave data are correlated with structural changes. In 
areas where these data are not available, general observations and/or documenta- 
tion of major storms occurring in the locality are presented along with the moni- 
toring data. Ground surveys are limited to the level needed to establish the 
accuracy of the photogrammetric techniques. 
Introduction 
